a u.s. official said petraeus was never a target of an investigation and that a tip about an affair led to that probe. now, general petraeus was scheduled to testify next week about the attack on the u.s. consulate in libya. now what happens now that he's gone? suzanne kelly is in washington with that part of this big story. >> susan, as washington reels from the announcement not only that david petraeus is stepping down from the post, but also from the admission he was having an extramarital affair, a u.s. official has said the counter intelligence unit was investigating a tip that he was having an affair because they needed to determine whether there was a potential security risk. the official telling cnn there was no suggestion that the fbi was investigating petraeus for any possible wrongdoing. now, if there were an official investigation focused on the cia director, that would have been something that the congressional oversight committees would have been briefed on. it's a matter of st